Children as young as five have been involved in "recreational rioting" in north Belfast, a senior police officer has revealed.
Officers in riot gear were struck with missiles
Assistant Chief Constable Duncan McCausland appealed for calm following rioting in the loyalist Woodvale and Shankill Road areas on Monday.
He said police had intelligence that text messages were sent around schools to plan further rioting for Tuesday.
Five people arrested on the Shankill were freed, pending further inquiries.
Mr McCausland said "a sinister element" was controlling the rioting.
"It's a very difficult situation, and I am calling on people to exercise restraint to calm the situation down," he said.
"I think it's very important that everybody in the community realises that we are their police service. We are not here to be used as a political football.
"My officers have to go up every single night into north Belfast to calm the situation down. We do not want to have to do that."
The UVF was blamed after petrol bombs, bricks and bottles were hurled at police and vehicles set on fire in the Woodvale area on Monday.
There were no injuries in the sustained rioting, which began after police moved in to carry out searches linked to a UVF "show of strength" on Saturday.
Mr McCausland said officers had to caution a five-year-old who they caught throwing stones on the Crumlin Road.
"He was taken home to his parents and handed over with a strong telling off," he said.
Later in the Shankill Road area, water cannon were deployed to halt rioting on Monday night as police came under attack.
Police have denied separate allegations of both inaction and heavy-handedness by officers.